Mrs McManus said: "This week's legal ruling on the energy from waste plant at Mallusk, has put at risk more than one billion pounds of strategic infrastructure projects and cast doubt over billions of pounds worth of projects still in the pipeline across the public and private sector.

"A lot of our members are extremely anxious around key infrastructure projects such as the north-south interconnector, the Belfast power station.

"We are really concerned that we are now in the vacuum where no one can make decisions."

Earlier on Thursday the secretary of state said she was "aware of concerns" over what decisions departments can make in the absence of ministers.